In heat exchangers one of the circuits of which is constituted by a bundle of tubes, difficulties are encountered at present in the positioning and the holding in place of these tubes. One difficulty resides in the fact that very often there exist differential expansions between the tubes which prohibits any absolutely rigid fastening at various points of the tubes. Another difficulty resides in the fact that, because the tubes are in a high speed fluid flow, vibration phenomena result in them, and it is then necessary to provide supports which damp these vibrations and which are distributed so that the free sections of the tubes do not exhibit a frequency of their own close to the frequency of the vibrations.
Such a problem of fastening a tube bundle is particularly important and delicate in the case of a speed generator of the sodium-water type in which the water-steam circuit is constituted by a tube bundle extending inside a vessel in which hot liquid sodium circulates. The essential difficulty inherent in the steam generator of the sodium-water type arises from the fact that liquid sodium possesses excellent thermal conductivity, a property which is of considerable value but which inflicts on the tube bundle violent temperature variations in transient operation, resulting in considerable differential expansions in these tubes.
Various support devices for the tube bundle have already been proposed, but these have certain drawbacks, especially relatively high complexity, risk of distortion or of wear of the tubes at the level of their clamping by the support, lack of control of the level of internal stresses developing in the tubes, due to the fact of their differential expansions, and a lack of constancy in time of the fastening and anti-vibration characteristics.